NP6 processors clear the iph.flags.reserved bit. This results in the packet checksum becoming incorrect because by default the packet is changed but the checksum is not recalculated. Since the checksum is incorrect these packets may be dropped by the network stack. You can enable this option to cause the system to re-calculate the checksum. Enabling this option may cause a minor performance reduction. This option is disabled by default.
To enabled checksum recalculation for packets with the iph.flags.reserved header:
config system npu
set iph-rsvd-re-cksum enable